Bone conduction audiphone



Oct. 14, 1 941. w. A. ZARTH BONE GONDUGTION AUDIPHONE Filed Feb. 5, 1940 NTOR ` Patented Oct. 14, 1941 BONE coNDUc'rioN AUmPnoNn William A. Zarth, Jamaica, N. Y.,- assignor to Dictograph Products Company, N. Y., a corporation of Delaware Inc., New' York,

Application February 5, 1940, serial No. 317,259

8 Claims.

This invention' relates to -audiphones and has particular reference to audiphone receivers having a vibrating element adapted -to be placed in operative connection with the bone` structure ofthe user for transmitting therethrough to the inner ear the audible sounds able microphone.

In Patent No. 2,144,458, issued January 17, 1939, to Henry Koch, there is disclosed a form of bone conduction audiphonereceiver' which compicked up byl a suitduction audiphone receiver of this ,invention not only includes all the advantages of that general type ofdirect action receivers but also the advantages of the reaction type. Without embodying bines the advantages' of the-reaction type 1 'e ceiver, in which a closed casing is vibrated bodily by reaction and communicates its vibration to A the bone. with the advantages ofthe so-called button type receiver, in`which a button is directly vibrated. against the bone, and the present invention is directed to an improvement on the aforementioned form of receiver disclosed in said patent.

In accordance with the present invention, a

the disadvantagesl ofeither, so that, with the advantages inherent iniits-structure a more effectiveand efli'cient instrument is provided.

For a more complete understanding ofthe in' vention, reference may be had to the accompanying drawing, in which:

- Figure 1 is a. longitudinal section through the casing of the new bo/ne conduction audiphone receiver of this invention and illustrating the interior thereof, aswell `as a schematic circuit bone conduction audiphone receiver yis provided in which the advantages of the reaction type in so far as immunity to pressure `on the casing, sealed casing and powerful vibrations are concerned, are combined With the advantages of the button or direct action type in so far as low power consumption, highquality roproduction and direct concentration of the reed vibrations on the bone are concerned, in addition to certain novel features of construction and operation peculiar to the present invention.

In a preferred embodiment of the present invention, the electromagnetic means carries the reed, which is vibrated relatively to the means when the latter is energized by voice currents,

and the enclosing casing is secured to the reed,

so that when the electromagnetic means is supported as by a headband, with the contactor side of the casing placed in operative connection with the bone structure of the user, the vibrations of the reed are transmitted directly therethrough to the inner ear, without vibration of the relatively heavy magnetic structure or the headband. rPhe headband connection to the magnetic structure enclosed within the casing is made through an opening in the latter providing `suilicient clearance for the headband connection to avoid vsupincluding the receiver;

Fig. 2 is a transverse section seen along the line 2-2 of Fig. l;

Fig. 3 is a plan view of the receiver with the casing cover removed; and yFig. 4, is a fragmentary longitudinal section therethrough, as

through the receiver and illustrating a modified L form of headband connecting arrangement.

Referring to the drawing, lthe bone conduction receiver includes the casing I0 ofhard rubber,

4 tactor I2 by means of a rivet I pression of the vibration of the casing. Preferably this opening is sealed against dirt land moisture by resilient sealing means interposed' be'- tWeen the Wall opening and the headband connection, and vthis means also prevents suppression of the vibration when excessive pressure is inadvertentlyapplied to the headband.

It will be seen that the direct acting bone conphenolic resin, or the like, comprising the cover II and the face plate'IZ rigidly secured to the cover I I by screws or the vlike passing through holes I3, so that a unitaryrenclosure is formed.

'I'he plate I2 is adapted to operatively engage theA bone and accordingly serves as the contacter. An electric cord I4, connectible byl separable electrical connectors I5 to the electromagnetic energizing means within the casing Ill', includes two wires I6 in circuit with the battery or other powmicrophone ortranser source Il andwith the mitter I8.l Suitable amplifying means, not

' shown, is usually provided.

Secured at one end to the face plate or-con 9 is a flat reed 20. which though substantially free at its other end, is nevertheless relatively stiff-so as to resist substantial flexing. This free end `of the reed 2U is centered between abutments 2| on the base plate I2 and is provided with an enlargement 22 to which is secured by stud bolts 23 the relatively stiff upwardly-extending spring 24. I

Secured by screws 25 at one end to'spring 24 so as to extend cantilever-fashion in substantially parallel spaced relation to reed 20 is a permanentbar magnet 26;, Rigidly mounted by studv bolts 21 on the free end of magnet 26 and depending therefrom toward the reed 20 is the pole piece 28 forming with the adjacent surface of the reed 20 a-narrow air gap 29 having a width on the order of a few thousandths of an inch.

The voice coil 30 is mounted on pole piece 28 and its terminals are connected by filamentary wires 3I to connecting strips 32 secured to studs 2I by screws 3 3 and extending along the face plate I2 into a cavity in the end of the cover II. The upturned ends 34 of these strips 32 form contact springs urging corresponding contact `pins 35 intofrictional and electrical contact with corresponding connectors I5, so that voice coii 38.

with the bone structure of the user, such ask the mastoid eminence. Energization of the voice coil 30 by currents within the audible frequency range, results in relative vibration between the reed 20 and the magnet 26 in the manner described. Because the magnetic structure is held microphone I8 varies the ilux across the air gap 29 and causes relative movement between the reed and the remainder of the electromagnetic means, as provided by the semi-flexibility of the spring 24. For purposes of this disclosure, the reed 20 is considered as a separate element, whereas the magnet 26, pole piece 28 and voice lcoil 30 are considered as the electromagnetic means. However, it is to be understood that the invention is not limited to this interpretation, for within the scope of this invention the electromagnetic means, or its equivalent, may be any electrical arrangement whereby relative vibratory movement is imparted to the reed v2l), or its equivalent, in response to energization by audible frequency currents.

Preferably formed integrally with the pole piece 28 are a pair of arms 36 extending rearwardly and parallel to the opposite sides of the magnet 26, so as to be rigid with respect thereto.

Screwed into the free end of each of these arms 36 is a laterally extending stud 31 having ,a concentric socket 38. The studs 31 pass through corresponding enlarged openings 39 in the side walls of the casing II and lie substantially flush with the surface thereof with the socket 38 readily accessible. It will be observed that the cover II of the casing I0 cannot be placed over or removed from the electromagnetic means on'A base I2 unless the studs 31 are removed, so that in' assembly, the cover II must first be emplaced on base I2 and then the studs 31 are inserted through the openings 39 and screwed in place into arms 36, .the studs 31 thus becoming an integral part of the electromagnetic .structure consisting of the parts 26, 28, 30 and 36, which vibrates relatively to the reed 20 and casing I0, and vice versa.

Adapted to be inserted into the exposed socket 38 at opposite sides of the casing I0 for pivotal connection' therewith are the pins 40 extending inwardly from 'the corresponding tines 4I of the fork 42 ofthe headband 43.l Because the fit between pin and the .socket 38 is close, the

stationary on the headband 43 in the manner described, the reed 28 and casing IIl vibrate relatively thereto and to the headband 43, and the vibration of the contactor I2, which is part of thecasing I0, is transmitted through the connected intervening bone structure to the inner ear of the user, who accordinglyhears the sounds picked up by the microphone I8.

Inasmuch as neither the heavy magnetic structure nor the headband is vibrated and as the casing I0 is light in weight, the consump- .tion of power is lowervthan withthe reaction type receiver. Also, since the vibrations of the reed I2 are directly applied to the bone, thepressed toward the contactor I2 with sufficient.

force to overcome the stiffness of the spring 24, the rubber sleeves 44 ofthe studs 31 prevent this excessive pressure from closing the air gap 29 or otherwise temporarily suppressing the vibration. Moreover, since the headband pivot axis, passing through sockets 38, is spaced rear- 'wardly from the air gap, toward the spring 24,

the effect on the air gap of anyexcessive pressure on the headband is minimized.

Instead of employing al pivoted type of headband or holder, a straight rigid connection. to the headband may be used as indicated in Fig. 4. There the pole piece 28' is provided with lateral extensions 36'v as before, but with the upper edges thereof extending above the magnet 26 and turned inwardly at 45 to form a channel into which the end 46 of the headband 43' firmly fits, so that the headband holds the magnet 26 stationary therewith. A rubber gasket 44 interposed between headband extension 46 and the connection of the magnetic structure to the' headband is firm, and since the headband forms a stationary support when the device is in use, it holdsthe magnetic structures 26, 28, 38, 3.6

4and 31 stationary whilethe reed 30 and casing I0 vibrate relatively thereto.

Preferably a short length of soft rubber tubing -44 encircles each stud 31 as a sleeve and fills the annular gap between the stud and the wall of the opening 39 in the casing I0. This rubber sleeve 40 does not restrain the vibration described, but prevents closing of the gap 29 during excessive pressure between the headband and the casing I0, as well as inhibiting the entrance of dirt andmoisture into casing I0.

In operation,the headband 43, or otherA supporting means connected firmly to the studs 31,

holds the contactor I2 in operative connection of Figs. l to 3 inclusive.

walls of the corresponding opening inA casing| I0 serves the same functions as. sleeves 44 in Fig. 2. It will be understood that the operation of the modification of` Fig. 4 is the same as that While cer-tain preferred embodiments of this invention have been illustrated and described herein, is not limited thereby, I changes in form and detail withinth the appended claims.

1. In a bone-conduction audiophone, the comscope of bination of a casing having a surface serving as a contactor adapted to be operatively connected with the bone structure of the user, said casing having openings in the opposite sides of the wall thereof, electromagnetic means within said casing including a magnet member,

a voice coil adapted to be energized by varying currents within the audible frequency range and a reed member magnetically coupled to said coil and resiliently connected to said magnet member, means securing one of said members to said contactor, mechanicalA coupling means secured to one of said members and extending through said openingsinthe `opposite sides of suppress the vibration,4

it is to be understood that the invention. but is susceptible of Y' transmits said vibrations through the bone to the wall of said casing and supporting means' rmly. connected to said mechanical coupling means for holding the corresponding member substantially stationary for vibration of\ saidother member relatively thereto when said voice coil is energized, whereby the contactor transmits said vibrations through the bone to the inner ear when connected thereto by saidsupl porting means.

2. In a bone-conduction audiphone, the combination of a casing having a surface serving 1 as a contactor adapted to be operatively connected with the bone structure of the user, saidy casing having openings in its opposite side-walls. A electromagnetic means within said casing and including la voice coil adapted to be energized 1.*

connected to said mechanical coupling means 2 for holding said electromagnetic means substantially stationary for vibration of said reed andv connected casing relatively thereto when said voice coil is energized, whereby the contactor the'inner ear when connected thereto by said supporting means. y v

3. In a bone-conduction audiphone, the combination of a casing having a surface serving as a contactor adapted to be operatively connected with the bone structure ofthe user, said casing having openings in its. opposite side walls., electromagneticmeans within said casing having an air gap and including .a voice coil adapted to be energized by varying currents within the audible frequency range, a reed magnetically coupled to said meansl across saidv air gap and secured to `said casing, relatively stiff spring means connecting said vreed and electromagnetic means and affording. limited' relative movement between them,v mechanical coupling means -at opposite sides of said electromagnetic means and rigidly securcdmthereto, and supporting `means firmly connected to said mechanical coupling means through said openings inthe wall of said casing` at a point spaced from said air gap for holding the electromagnetic means substantially stationi ing relatively thereto when said voice coil is enary for vibration of said reed and connected casergized, whereby the contactor ytransmits said vibrations through the bone t9 the inner ear when 'connectedthereto by said supporting means` 4. In a bone-conduction`,audiphone,'the combination ofv a casing having a surface serving as,l a contactor adapted to be operatively connected with the bone structure ofthe user, said casing having openings in its opposite side walls, electromagnetic means within said casing and including a voice coil adapted to be energized by varying currentswithin the audible frequency. range, a reed magnetically coupled to said means and secured to said casing, relatively stiil spring means connecting said reed and electromagnetic means and affording limited reiativemovement 7 between them,` lateral extensions rigidly connectedl to opposite sides of said electromagnetic means and projecting atleast partially through said corresponding openings in the side walls of l Atransactie said casing, and supporting meansiirmly conthrough the bone to the inner ear when con- 'nected thereto byf said supporting means.

5. In a bone conduction audiphone, the combination vof a casing having a surface serving as` a contactor adapted to be operatively connected with the bone structure of the user, said casing having openings in Aits Opposite side walls, electromagnetic means within said casing and including'a voice coil adapted to be energized by varying vcurrents within the audible frequency range, a reed magnetically coupled to said` means and secured to said casing, relatively stiff spring means connecting said reed and means and af-` fording limited relative movement between them,v

lateral extensions rigidly connected to opposite sides of said electromagnetic means and projecting at least partially through said corresponding openings in the side walls of said casing, and supporting means-pivotally connected to said extensions for holding the electromagnetic means substantially lstationary for vibration of said reed and connected casing relatively thereto when said voice coil is energized, whereby the contactor transmits said vibrations 'through the bone to the inner ear when connectedthereto by said supporting means.

6. In a bone-conduction audiphone, the combination of a casing having a surface serving as al contactor adapted to be operatively connected with the bone structure of the user, said casing having openings in its opposite side walls, elec-` tromagnetic means Within said casing and including a voice coil'adapted to be energized by I varying currents within the audible frequency 40 range, a reed magnetically coupled to said means and secured to said casing, relatively stii spring means connecting saidreed and electromagnetic means and-affording limited relative lmovement' between them, supporting means extending through said openings in the wall of` said casing and firmly connected to said electromagnetic ,c

means at a point between said coil and spring means for holding the same substantially stationary'for vibration of saidreed and connected casing relatively thereto when said voice coil is energized, wherebyjthe contactor transmits 'said vibrations through the bone to ythe 'inner ear when connected thereto by said supporting means, and resilient means'interposed between supporting means and the adjacent wail of the casing foi-'limiting relative movement between them under excessive pressure.l

7. In a bone-conduction audiphone, the combination of a casing having a surface serving as a contactor adapted to be operativelyconnected. with the bone structure of the user, said casing having openings in its opposite side walls, `elec tromagnetic means within said casing and including a voice`coil adapted to be energized by varying currents within the audible frequency range, a reed magnetically coupled to said means and secured'to said casing, relatively stiff spring means connecting. said reed and electromagnetic means and affording limited relative movement between them, lateral ,extensions rigidly con-- nected to opposite sides of said electromagnetic means and projecting at least partially through said corresponding openings in the side Walls of nected tosaid extensionsv-forholdingfthe elec` tromagnetic means substantially stationaryforav netic means substantially stationary for vibration of said reed and connected casing relatively thereto when said voice coil is energized, whereby the contactor transmits through the bone to the innerear when con-t nected thereto by said supporting means, and resilient means interposed between said vextensions and the edge of the corresponding openings in the wall of the casing for limiting relative movement between them under `excessive pressure.

8. In a bone conduction audiphone, the coinbination of a casing having a surfaceserving as a contacter adapted to be operatively connected with the bone structure of the user, electromagnetic means Within said casing and including a voice coil adapted to be energized-by varying currents within the audible 'frequency said vibrationsrange, a reed magnetically coupled to said means and secured to said casing, relatively still. spring means connecting said reed and electromagnetic means and affording limited relative movement between them, a mechanical coupling member rigidly. securedv to the magnet of said electromagnetic means and-extending at' opposite sides of said magnet, said casing having openings in its opposite walls registering with s'aid mechanical coupling member, supporting means, and aligned pivots connecting said supporting means to said l mechanical coupling member through said casing openings, whereby said supporting means is firmly connected to said electromagnetic means for holding the latter stationary for vibration of said reed and connected casing relatively to said supporting and electromagnetic means in use.

- WILLIAM A. ZARTH. 

